Please help me with the problem.

Viviani's Curve is also attached below.

2.3.4 Let y(t) be a unit-speed curve with k(t) > 0 and r(t) # 0 for all t. Show that, if y is spherical, i.e., if it lies on the surface of a sphere, then (2.22) K ds T Conversely, show that if Eq. 2.22 holds, then p2 + (po )? =12 for some (positive) constant r, where p = 1/k and o = 1/7, and deduce that y lies on a sphere of radius r. Verify that Eq. 2.22 holds for Viviani's curve (Exercise 1.1.8).1.1.8 Show that y(t) = (cost - -, sint cost, sint) is a parametrization of the curve of intersection of the circular cylinder of radius , and axis the z-axis with the sphere of radius 1 and centre (-,, 0, 0). This is called Viviani's Curve - see above